Measuring Population
Change
 2 aspects of population that
demographers want to know more
about: size and rate of change
 Size = actual number of people in a
population at a given time in history
 Rate of change = how a population
has changed over a period of time.
Often referred to as population growth
(pop. rarely shrinks)
Absolute vs. Relative
 Absolute population change- actual
number of people that a population
has increased or decreased by over a
period of time
 Relative population change (or
population growth rate) – average
annual percentage change over this
same time period
Relative population calculation
 Find the absolute change (change from
one time period to another)
 Divide the absolute change by the
original population and multiply by 100
(gives a % of change)
 Relative change stated as an annual rate
so % must be divided by the number of
years over which the population change
took place
Example
1. Country A- population 1970 = 21 089 000
population 1990 = 27 297 000
2. Absolute change = 27 297 000 – 21 089 000
= 6 208 000
3. % of change = absolute change / 1970 pop. *
100
6 208 000 / 21 089 000 * 100 = 29.4
4. Annual growth rate = % of change / # of years
29.4 / 20 years = 1.47
Calculate the relative population
change for the following
countries…
Country A- 1970 population = 90 840 000
1990 population = 150 400 000
Country B – 1970 population = 4 703 000
1990 population = 5 020 000
Factors affecting population change
4 factors:
– Number of people born
– Number of people who die
– Number of people who move into the country
– Number of people who leave the country
Because these stats are so important they are
called vital statistics
Birth and Death Rates
Rates of fertility (birth) and mortality
(death) are recorded as the number of
birth or deaths per 1000 people per year
Eg. Canada’s birth rate in 1998 was 12/
1000
Because these rates are calculated on the
basis of the entire population, regardless
or age or sex, they are termed crude rates
Rate of natural increase
 Birth rate (BR) – death rate (DR) =
annual rate of population growth OR
the rate of natural increase (RNI)
 BR/ 1000 – DR/ 10000 = RNI / 1000
 Population growth usually expressed
as percentage therefore have to
convert
Example
In 1998 Canada’s BR/ 1000 = 12
DR/ 1000 = 7
BR/ 1000 – DR/ 1000 = RNI/ 1000
12- 7 = 5
RNI/ 1000 = 5/ 1000
To change to a % :
Convert denominator to 100 = 0.5/ 100
= 0.5% per year
Calculate the RNI in % for the
following…
 Algeria – BR = 31, DR = 7
 Niger- BR = 53, DR= 19
 Japan- BR = 10, DR = 7
 Dominican Republic- BR= 27, DR= 6
 Afghanistan- BR= 43, DR= 18
 Norway- BR= 14, DR= 10
 South Africa- BR= 27, DR= 11
 Colombia- BR= 27, DR= 6
Factors Influencing Birth Rates
 Number of women in pop.
 Age of women in pop.
 Economic status and education levels of
women
 Culture and religious beliefs
 Medical conditions and general level of
health care
 Government population policies
Factors influencing death rates
 Availability of medical services and costs
associated with them
 Contraction of preventable diseases
 Education
 Availability of clean water and food
 Level of economic development
 Environmental disasters
 Countries fertility rate
Fertility rates
 Closely related to birth rates
 Total fertility rates (TFR)- average number
of children a women would have in her
lifetime if the annual birth rates remained
constant
 Tends to be higher in LDC’s
Replacement levels
 The amount of children each woman
needs to have to maintain the countries
level of population
 Eg. 2.1 children / female in a MDC and
about 2.5 children / female in a LDC
Migration
 People moving in and out of a country
 2 types:
Immigration- people moving to a country
Emigration- people moving out of a
country
Push and Pull Forces
 Conditions that help us understand the
forces that cause migration
 Push forces- conditions in home country
that make a person want to leave (ex.
Lack of jobs, poor education system)
 Pull forces- advantageous conditions in
receiving country that draw a person there
(ex. Good social programs, friends and
family)
Refugees
 Due to worsening political and
economic situations in many areas of
the world means that push factors out
weigh the pull factors
 Refugees are people escaping war,
life-threatening discrimination, famine,
floods, and other natural disasters
 They must enter the new country
without permission therefore they do
not have any legal standing
 Some governments welcome
refugees as new citizens on
humanitarian grounds. Other
refugees will have to return to their
homeland once conditions there have
improved